Liquid-fuel-ignition mechanism



A. DOBLE. LIQUID FUEL IGNITION MECHANISM.

APPLICATION FILED AUG.27, I9I7- 1,349,877. Patented Aug. 17, 1920.

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A. DOBLE.

LIQUID FUEL IGNITION MECHANISM. APPLICATION FILEDIAUGJII 1917..

Patented Aug. 17, 1920.

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ABN'E-R DOBLE, OF DETROIT, MICHIGAN, ASSIGNOR, BY MESNE ASSIGNMENTS, T0

DOBLE-DETROIT STEAM MOTORS 00., or DETROIT, MICHIGAN, A CORPORATION OF DELAWARE.

LIQUID-FUEL-IGNITION MECHANISM.

Specification of Letters Patent.

Patented Aug. 17, 1920.

Application filed August 27, 1917. Serial No. 188,502.

To all whom it may concern:

Be it known that I, ABNER Donne, a citizen of the United States of America, and resident of Detroit, Wayne county, Michigan, have invented a certain new anduseful Improvement in Liquid Fuel Ign1 t1on Mechanism, of which the following 1s a specification. I

My invention relates to the art of burmng heavy hydrocarbons which are non-volatile or substantially so at normal temperatures, and my invention concerns a means of 1nstantaneous ignition or initiation of combustion of such hydrocarbons in their normal temperature condition.

My invention has its application In connection with the utilization of heavy hydrocarbons, such as kerosene and distillate, as fuel for the rapid generation of steam in the power-plant of steam-driven automobiles, wherein the elimination of the annoyance and delay of pro-vaporization of the fuel and the rapid generation of steam are essential requisites in a commercially successful automobile.

Heavy liquid hydrocarbons such as kerosene can, as I have found in practice, be very effectively and completely burned, without pro-heating or pre-vaporization, from an initially normal or so-called cold temperature condition and extremely high temperatures obtained for the generation of steam, by the atomization process of finely dividing or pulverizing the liquid and mixing it with proper amount of air to support combustion and confining the combustion in a closed refractory chamber which attains an intense incandescent temperature. The hydrocarbon at normal temperatures may be atomized or broken up and mixed with the proper proportion of air to complete combustion within said chamber, or the air which supports combustion may be used as the atomizing agency for finely dividing the hydrocarbon and projecting it into the combustion chamber. In any event, however, there must be a suflicicnt proportion of air in the mixture to complete combustion in the combustion chamber, without any smoke or soot Whatever, else the very advantage attendant upon a utilization of the atomizing method-in a steam driven automobile power plant, is lost. As before mentioned,'I have found in practice that a mix- -but a mixture such as I ture of the atomized fuel and air burned in a chamber in the manner above mentioned can be completely consumed without soot and smoke, but such a mixture (which I will refer to for convenience as the main or completely combustible mixture), has a relatively excessive proportion of air and a relatively small proportion of atomized fuel. In other words, relatively speaking, this mixture is rich in air and lean in hydrocarbon.

The extreme desirability in an automobile power plant, of instantaneous initiation of combustion fuel, and the use of an electric spark for this purpose, is at once obvious,

have just described Wlll not ignite at normal temperature by means of an electric spark, although, after having been properly ignited, it will sustaln complete combustion in said chamber. So far as I am able to ascertain, the failure of this mixture to ignite from a spark is due to the fact that a spark of practical proportions, although intensely hot, is comparatively small in volume, and in such a relatively lean mixture the particles of fuel are separated in a comparatively large volume of air to such an extent that the air absorbs the heat and prevents the transmission of heat to adjacent particles from those ignited. Furthermore, if in addition the body of mixture is moving at comparatively high velocity, the particles do not remain in the small zone of heat of the spark long enough to.

become ignited.

I have discovered, however, that a mixture of finely divided hydrocarbon and air at the normal atmospheric temperatures can readily be instantly ignited by an electric spark if the mixture is excessive or rich in hydrocarbon and lean in air, but on the other hand a mixture of this character is not completely combustible, there being insuificient air therein to entirely or com-- pletely consume the hydrocarbon even under the most favorable conditions. Hence such a mixture (which for convenience of reference I will term the auxiliary or incompletely combustible mixture) is not adapted for continuous combustion purposes because it burns incompletely, is productive of smoke and soot, disagreeable odor and would not develop the necessary tempera- -ture if used in an automobile power plant.

As before mentioned, however, this mixture will readily and repeatedly ignite by an electric spark because, so far as I am able to ascertain, the particles of hydrocarbon are relatively close together and not diluted with air to any reat extent. Hence the heat generated by t e s ark, although small in volume, is readily issipated and absorbed into the fuel particles instead of air, and the particles in the immediate heat zone ignite and readily transmit their flame to the adjacent particles, thus instantly building up a body of flame throughout the mixture. Now, by utilizing the characteristics of both of these mixtures,I am able to bring about without pre-vaporization, the instantaneous ignition of a completely combustible mix-- ture at normal temperature for the sustained or continued production of heat by means of an electric spark, which result, in the case of an automobile power plant, leaves nothing for the operator to do but to start the v sparkin and mixture forming mechanisms,

and which in practice amounts to nothing more than the operation of an electric switch.

I acomplish these results by producing a main mixture of finely divided liquid normally non-volatile hydrocarbon and air in suflicient proportions to completely ,burn this hydrocarbon, and a second incompletely combustible or auxiliary mixture of smalle1 volume, the second mixture being arranged in igniting relation to said main mixture, and in the zone of the auxiliary mixture I introduce an electric spark. The heat of the spark ignites the auxiliary mixture which transmits its flames to and ignites the main mixture. The flame of the auxiliary mixture need be maintained only for suflicient period of time to bring about the ignition of the main flame.

The object of my present invention is to provide an improved mixture-forming and ignition mechanism for automobile power plants, which mechanism will produce a combustible liquid fuelmixture and will instantaneously ignite or initiate combustion in said mixture at normal temperature.

Other objects of my invention will appear hereinafter.

The accompanying drawings illustrate an automobile power plant structure which embodies my invention and which accomplishes the desired results.

In the drawings Figure 1 is a sectional view through the blower, a portion of the combustion chamber, and one of the atomizers of the fuel spraying mixture forming and ignition mechanism embodying my invention.

' Fig. 2 is a transverse sectional view of the structure shown in Fig. 1, taken substantially on the line 22 of Fig. 1.

Fig. 3 is an enlarged detail section of the fuel nozzles for prbducing the different mixtures of fuel and air.

Fig. 4 is a view in diagram illustrating driven by means of an electric motor 13 mounted on the blower casing. The blower has its outlet 14 divided into two sections 15 extending horizontally and in parallel relation and the ends of these sections are removably fastened to the wall 16 of the inclosure within which is positioned the refractory firepot 16 forming the combustion chamber. The combustion chamber is shown in position beneath a steam generator 16 of an automobile power plant, this chamber being arranged to inclose the lower end of the generator casing so that the heated products ofcombustion will risedirectly in said generator. The end portions ofthe blower outlet sections are tubular and contain removable Venturi tubes or members 17, and within the-combustion chamber there is provided a casting 18 having two tapered passages 19 which are alined with and form continuations of the Venturi tubes, to direct the sprays of fuel mixture into the combustion chamber. The Venturi tubes are of course tapered to a restricted throat portion 17 so as to increase the velocity of the air passing therethrough and at these throat portions are fuel nozzles which supply the fuel to be atomized. These fuel nozzles are formed by the small Venturi tubes 20 mounted upon upstanding posts 21 on a common manifold member 22. The small nozzle tubes are provided with tapered passages and are positioned centrally with respect to the Venturi tubes 17. The liquid fuel is admitted to these tapered passages through the openings 23 in the upper sides, these openings communicating with the annular passages 24 formed by grooves on the outer surface of the nozzle tubes. The upper ends of the posts have rings which support the point somewhat below the fuel nozzles, and in order to raise the fuel to the float valve through the feed pipe 30, I provide air pressure of a few pounds in the tank. This pressure is supplied by a hand pump 21 connepted by pipe 32 with the fuel tank above the level of the oil. The blower as before mentioned provides a constant blast or current of air through each of the Venturi pas sages, and in acordance with the principles of atomization draws the liquid fuel from the nozzles and pulverizes or finely divides it, a portion of the current of air being diverted through the small nozzle passages to assist in breaking up the fuel, thus producing sprays of fuel from the nozzles, which at the ends of the nozzle tubes is mixed with great volumes of air. This action produces a mixture of fuel and air in such proportions as to support complete combustion in the fire-pot. A dilute mixture of this character wherein there is a proper proportion of air to support complete combustion will burn without soot, smoke or odor and will supply the volume of heat necessary for the rapid generation of steam and can be readily controlled after having been ignited, but such a mixture is entirely incapable of being ignited at normal temperature by the small flame of an electric spark or equivalent i nition means of practical proportions an of instantaneous operation. I therefore arrange the structure so that it will also produce a different mixture of fuel and air which is capable of ignition by an electric spark, and the flame of this spark ignitible mixture is utilized for the ignition of the main combustible mixture. I accomplish this by the provision of supplemental nozzles 34 which are positioned so as to spray additional atomized fuel into the main nozzles, and thus enrich or superimpose upon the main mixture at the main nozzles a rich mixture which is capable of instantaneous ignition by an electric spark or its equivalent. In the case of these supplemental sprays the fuel is preferably broken up mechanically by projecting the fuel under considerable pressure from the nozzles and against the abutments or pins 34 positioned directly in front of the nozzles and fastened to the main nozzle tubes. And for the purpose of conveniently obtaining sufiicient pressure for the fuel I utilize the compressed air in the fuel tank. This results in an extremely fine degree of atomization, and these finely atomized sprays of fuel are projected into the main nozzle tubes. Under these conditions the sprays of fuel mixture at the main nozzles are of such proportion that they will readily ignite from a cold condition by a spark, and the flames from the burning sprays will instantly ignite the mixture produced by the blower air and main nozzles. The spark for ignition purposes takes place between the electrodes 3:) and 36 just within the ends of the main nozzle tube passages. The electrodes 35 are formed by projections in the main nozzles which are suitably grounded at 37, while the other electrodes 36 are carried by spark plugs 38, screwed into the Venturi tube members and connected to the secondary Winding 39 of a suitable spark coil, by means of the conductors 40.

The mixture which is thus produced and which is capable of spark ignition, however is incompletely combustible and can not supply the necessary heat for the purposes of generation of steam, and burns with smoke and soot. Its volume however is relatively small as compared to the main sprays and if not continued too long its smoke and soot will be consumed in the combustion chamber. As a matter of practice the duration of the ignition mixture need be but momentary because the matter of time from the initiation of the spark until the main sprays become ignited is practically instantaneous. For these reasons it is advisable to maintain the ignition mixture for very short periods of time, when required to ignite the main mixtures, and in the Fig. 4, I illustrate, a controlling system which automatically determines the period of dura tion of the ignition flame and spark igniter. In the supply pipe 41 which leads from the fuel tank to the supplemental nozzles is a valve 42 which controls the flow of fuel to the nozzles. This valve has a fuel passage controlled by the valve member 43, and is normally held closed by the spring 43. The valve is operated however by a diaphragm 43 which is subject to air pressure in the diaphragm chamber. The controlling mechanism involves an air storage tank 44 capable of holding a charge of air under pressure sufficient to operate the diaphragm valve for the period of time it is desired to operate the supplemental nozzles. This tank or reservoir is illustrated larger than the fuel tank for the sake of clearness of illustration, but it will be understood that in practice it is smaller and of considerably less capacity than the fuel tank, the fuel tank being capable of holding sufficient compressed air to charge the reservoir tank many times. The reservoir tank has a passage 45 connected by pipe 46 with the compressed air supply in the fuel tank. and this passage is controlled by a valve 47 at one end of the valve stem 48. This valve is maintained normally open to keep the tank supplied with air, by means of the spring 49. A pipe 50 leads from the tank or reservoir to the diaphragm valve chamber, and the tank outlet is controlled by a valve 51 on the lower end of the valve stem 48, this valve being normally closed by the spring 49.- When the lower valve is opened and 'the upper valve closed the charge of air the reservoir will operate the diaphragm valve, this latter. valve chamber having a bleed hole 52, until the charge of air is dissipated, whereupon the diaphragm valve will tery 57 over. the circuit conductors 58, 59

and 60 to ground. The valve stem also carries a switch member 61 which closes the motor circuit 62 through the contacts 63 so that when the operator closes the manual switch 56 the ignition mechanism and blower will be started simultaneously. In the event that the air pressure in the reservoir or fuel tank should fail and prevent the operation of the ignition mechanism, it is not advisable to start the main atomizers and fill the combustion chamber with fuel- Hence a diaphragm switch 64 is provided which is subject to the air pressure in the reservoir and which normally holds the cir cuit of the solenoid closedat the contact 65. Of course, if no air pressure exists in the supply, the contact is held open and the operators switch has no effect on the system. The circuit 66,- which includes the primary winding 67 of the spark coil is also controlled by a diaphragm switch 68 similar to the switch 64 so that while pressure exists in the reservoir the spark coil circuit is closed, but when the charge of air has been exhausted this circuit is opened and the spark discontinued simultaneously with the discontinuance of the supplemental nozzles. The control system which I have herein described constitutes subject matter of my copending application Serial No. 178,513, filed July 3, 1917.

I claim 1. In a liquid-fuel burning apparatus, a mainatomizer for forming anon-spark-ignitible mixture, an auxiliary atomizer so positioned as to throw an additional spray of liquid fuel directly into the spray of said main atomizer whereby said sprays combine to form an enriched mixture capable of ignition by an electric spark, an electric sparker mechanism, and means to operate said auxiliary atomizer during the' operation of the sparker mechanism, these means embodying devices whereby the operation of the auxiliary atomizer is stopped after nonlilentary operation, for the purpose set ort 2. The combination of a Venturi tube, a

he valve stem is operated nozzle, and an air' blower for 'su plying air 1 to said venturi to atomize the uel in said tubular fuel nozzle.

3. The combination of a Venturi tube, an 6 air blower adapted to suppl a large volume of low pressure air to sai venturi, a fuel nozzlein said venturi in as irating relation to said air supply, a sec'on ranged to spray atomized fuel into said venturi, means for supplying liquid fuel under pressure to. said second nozzle, and

an igniting device for igniting the spray from said second nozzle.

4. In an igniting device, the combinat1on ofvan alr passage conta nlng a Venturi -tube, means for forcing air through said venturi, a liquid fuel nozzle positioned in said venturi in aspirating relation to said air supply whereby an atomized orspra ed combustible is formed, a second liquid uel nozzle positioned in said air passage adf fuel nozzle ar- 5. The combination of a main li uid fuel atomizer for producing a spray of uel mix ture incapable of ignition by an electric spark, and an auxiliary nozzle positioned within said main atomizer to spray atomized fuel into said' mixture to produce another mixture capable of ignition by an electric tube nozzle to produce an incompletely com- I bustible mixture, an electric spark ignition device for igniting said incompletely combustible mixture, and means for momentarily supplying fuel to said supplemental nozzle.

7 The method of initiating combustion in a mixture of non-volatile hydrocarbon and air, consisting in forming a mixture of said hydrocarbon and air incapable of ignition by an electric spark, momentarily adding sufiicient liquid fuel to change said nonspark-ignitible mixture to a spark-ignitible mixture, igniting said spark-ignitible mixture by an electric spark and utilizing the flame from said spark-ignitible mixture to ignite the non-spark-ignitible mixture.

8. The method of initiating combustion in a non-spark-ignitible mixture of hydrocarbon and air, consisting in forming a mixture of said hydrocarbon and air sufficiently rich in hydrocarbon to become spark-ignitible, igniting said spark-ignitible mixture by an electric spark producing a flame, then reducing the quantity of hydrocarbon in the mixture to a point of rendering it non-spark-ignitible and utilizing the flame to propagate ii'iflanimation in the non-sparkignitible mixture.

9. In a liquid-fuel burning apparatus, a main atomizer for forming a non-sparkignitible mixture, an auxiliary atomizer so positioned as to throw an additional spray of liquid fuel directly into the spray of said main atomizer whereby said sprays combine to form an enriched mixture capable of ignition by an electric spark, an electric sparker mechanism, and means to operate said auxiliary atomizer during the operation of the sparker mechanism, these means embodying devices whereby the operation of the auxiliary atomizer is stopped after a predetermined quantity of fuel is supplied therethrough, for the purpose set forth.

10. In a liquid-fuel burning apparatus, a main atomizer constructed to form a nonspark-ignitible mixture only of air and hydrocarbon, an auxiliary atomizer adapted to form a spray of hydrocarbon only, this auxiliary atomizer being so positioned as to throw its spray directly into the spray of said main atomizer to thereby combine the two sprays to form an enriched mixture 'apable of ignition by an electric spark, an electric sparker mechanism, and means to operate said auxiliary atomizer during the operation of the sparker mechanism, these means embodying devices whereby the operation of the auxiliary atomizer is stopped after momentary operation, for the purpose set forth.

Signed by me at Detroit, Mich, this 23d day of August, 1917.

ABNER DOBLE. 

